ORIGINAL ARTICLE

Nutrient contents in bottom sediment samplesfrom a southern Brazilian microbasin

Marjore Antunes • Maısa Trevisan Antunes •

Andreia Neves Fernandes • Janaina da Silva Crespo •

Marcelo Giovanela

Received: 23 November 2011 / Accepted: 3 September 2012 / Published online: 15 September 2012

� Springer-Verlag 2012

Abstract The nutrients, carbon, nitrogen and phosphorus,

significantly affect the quality of aquatic environments,

especially when present at concentrations above natural

levels. In this context, the sedimentary column can act as

an environment for storage or accumulation of these

nutrients and for the reprocessing of such substances in the

water column and aquatic biota. In this context, this study

aimed to estimate the concentration of total organic carbon

(TOC), total nitrogen (TN), total phosphorus (TP), inor-

ganic phosphorus (IP) and organic phosphorus (OP) in

seven sediment samples that were collected from the

Marrecas Stream microbasin (Caxias do Sul, Rio Grande

do Sul State, Brazil). The relationships among the sediment

nutrient concentrations and the levels of organic matter

(OM), fine material (silt–clay) and the concentration of the

metal species, Al, Fe and Mn, as well as the possible

nutrient sources to the stream studied were also evaluated.

The data set suggest that the TOC and IP appear to have a

direct correlation with the vast riparian vegetation present

in areas adjacent to the sampling points and to the physico-

chemical properties of the water and sedimentary column.

Moreover, the results obtained for TN suggest that its

concentration possibly suffers interference from the tem-

perature of the water and its oxygenation, in addition to

other biological activities. On the other hand, one cannot

rule out human interference, mainly in the levels of OP,

possibly due to the inflow of domestic sewage to the

stream.

Keywords Sediments � Nutrients � Organic matter �Metal

species � Eutrophication

Abbreviations

IP Inorganic phosphorus

OM Organic matter

ON Organic nitrogen

OP Organic phosphorus

TN Total nitrogen

TOC Total organic carbon

TP Total phosphorus

Introduction

Water quantity and quality are factors that are directly or

indirectly influenced by population growth, regional eco-

nomic activities, irresponsible soil utilization and the indis-

criminate release of liquid and solid wastes into receiving

bodies (Froehner and Martins 2008; Souza et al. 2009). Many

chemical compounds, especially those containing carbon,

nitrogen and phosphorus, can influence the quality of a water

body. These elements are naturally present in aquatic eco-

systems, and their levels are influenced by their respective

biogeochemical cycles. Moreover, their concentrations can

vary depending on the temporal and spacial conditions. These

elements can be found in different forms in the environment

(i.e., organic, inorganic, dissolved or particulate) (Agemian

1997) and can therefore be present in both water and sediment.

Among the elements mentioned above, carbon is

undoubtedly the most abundant. According to Ouyang

M. Antunes � M. T. Antunes � J. da Silva Crespo �M. Giovanela (&)

Centro de Ciencias Exatas e Tecnologia, Universidade de Caxias

do Sul, Caxias do Sul, RS 95070-560, Brazil

e-mail: mgiovan1@ucs.br

A. N. Fernandes

Instituto de Quımica, Universidade Federal do Rio Grande

do Sul, Porto Alegre, RS 91501-970, Brazil

123

Environ Earth Sci (2013) 69:959–968

DOI 10.1007/s12665-012-1980-9

(2003), the presence of this element may affect the avail-

ability of the others nutrients and control the solubility and

toxicity of contaminants. Nitrogen is normally encountered

in its organic form. The main natural sources of nitrogen-

ated compounds, which mainly include peptides and

polypeptides, are cell lysis, decay and excretion by phy-

toplankton and aquatic macrophytes (Esteves 1998).

Phosphorus, however, is predominant in its inorganic form

and originates naturally in combination with Fe, Al, Ca

and/or clay minerals from the chemical weathering of rocks

(Zhang et al. 2007, 2008).

In addition to the natural occurrence of nutrients in the

aquatic environment, some point and/or diffuse sources of

pollution, such as sewage, agricultural waste and industrial

effluents, can carry some of these substances to water

bodies, harming the homeostasis of the environment

(Roessink et al. 2008). An excess of these nutrients causes

an increase in the productivity of the aquatic ecosystem,

thus affecting its quality and biota through a process known

as artificial eutrophication (Nyenje et al. 2010).

The sedimentary column, in this context, can act as a

repository for the storage or accumulation of nutrients, the

reprocessing of these materials and the exchange of

chemical species with the water column and aquatic biota

(Mozeto and Soares 2006). These exchanges may occur

through biological, physicochemical, chemical and trans-

port processes and usually occur in the direction of greater

to lower concentrations, resulting in equilibrium between

the two compartments (Baumgarten et al. 2001). The

availability of nutrients in the aquatic environment can also

be influenced by the hydrodynamics of the water body,

causing an increase in the chemical exchanges between

water and sediment, especially in shallow environments

(Baumgarten et al. 2001; Roessink et al. 2008). Therefore,

many studies have assessed the composition of sediments

using the concentrations of carbon, nitrogen and phos-

phorus to investigate aquatic ecosystem quality (House and

Denison 2002; Spooner and Maher 2009; Grenz et al.

2010).

Within this context, the objectives of the present study

were: (1) to estimate the concentration of total organic

carbon (TOC), total nitrogen (TN), total phosphorus (TP),

inorganic phosphorus (IP) and organic phosphorus (OP) in

seven sediment samples collected from the Marrecas

Stream microbasin (Caxias do Sul, Rio Grande do Sul

State, Brazil); (2) to investigate the relationships among

nutrient concentrations and the levels of organic matter

(OM), fine material (silt–clay) and the concentration of the

metal species, Al, Fe and Mn; (3) to discuss the possible

sources of nutrients to the stream studied; and (4) to

compare the results obtained with the literature. This

microbasin was chosen as the study area because it will

contain the newest dam and surface water treatment

complex for the public supply of the local municipality. It

is important to highlight that this area of the basin is

influenced by various activities, including livestock pro-

duction (cattle, pigs, horses, sheep, poultry), agricultural

use (fruit production, horticulture, forestry) and industry

(slaughter of sheep), in addition to residences and five

recreational areas (camping) (Schneider et al. 2009).

Materials and methods

Study area

The Marrecas Stream microbasin (29�0303400S and

50�5703500W) lies within the Sao Marcos River basin, which

is one of the main tributaries of the Taquari-Antas hydro-

graphic basin. Located in a predominantly rural area, this

microbasin has an area of 55.12 km2 and borders the Faxinal

Stream basin and the Sao Francisco de Paula municipality.

The stream begins close to the locality of Apanhador in the

municipality of Caxias do Sul (Rio Grande do Sul State,

Brazil) and is approximately 15-km long (Antunes et al.

2008). The map in Fig. 1 shows its location in the regional

context and the detailing at a scale of 1:20,000, in addition to

the aerial view of the sampling points.

The natural vegetative cover in the region around the

microbasin is characterized as mixed ombrophilous forest

(Araucaria Forest). With regard to climate characterization,

the region is located in a temperate zone with a meso-

thermal climate. Annual temperatures, on average, are

between 14 and 22 �C, and the average annual rainfall

varies between 1,250 and 2,000 mm. With respect to relief,

the watershed is located in the Brazilian southern plateau

with rocks belonging to the Parana Sedimentary Basin,

being dominated by a sequence of basalts and basaltic

andesites at its base and by dacites, trachydacites and

rhyolites in the upper portion of the sequence. These

geological features give the water of the Marrecas Stream

microbasin an acidic characteristic, and the water has sig-

nificant concentrations of Fe and Al, which can later be

incorporated into the sedimentary column.

Sampling

In this study, seven sediment samples (named 1, 2, 3, 4, 5,

6 and 7) were collected directly from the bottom of the

stream using a Petersen sampling device. Fresh sediment

samples were used for granulometric analyses. For other

tests, the samples were first dried at 50 �C for 24 h, sub-

sequently ground and then fractionated in a 250-lm sieve

for determining the OM levels. For analysis of the con-

centrations of nutrients and the metal species, Al, Fe and

Mn, the dried samples were fractionated in a 63-lm sieve.

960 Environ Earth Sci (2013) 69:959–968

123

All laboratory glassware and plastic used in the sam-

pling and preservation of sediment samples were first

washed with tap water and then soaked in a 15 % (v/v)

solution of alkaline Extran for 24 h. Next, it was washed

thoroughly with tap water and left in a 50 % (v/v) solution

of HNO3 for 24 h. At the end of this procedure, all mate-

rials were rinsed with distilled water and dried at room

temperature.

Sediment analysis

The chemicals employed in the sediment analysis were all

of analytical grade. Hydrochloric, nitric and sulfuric acids

and hydrogen peroxide were obtained from Merck. The

salts of potassium dichromate, ammonium ferrous sulfate

hexahydrate, ammonium molybdate tetrahydrate and

anhydrous potassium phosphate monobasic were purchased

from Vetec. Ascorbic acid and potassium antimonyl tar-

trate trihydrate products were acquired from Synth, and the

solution of the indicator ferroin was acquired from Tec-

Lab. All aqueous solutions were prepared with deionized

water.

The TOC content of the sediment samples was deter-

mined by exothermic heating and oxidation according to

the Mebius method proposed by Rheinheimer et al. (2008).

The dry sediments (approximately 0.25 g) were initially

Fig. 1 Study area and aerial view of the sampling points

Environ Earth Sci (2013) 69:959–968 961

123

mixed with 10.0 mL of a 0.067 mol L-1 solution of

K2Cr2O7 and 15.0 mL of concentrated H2SO4. The sus-

pensions were then heated at 150 �C for 30 min in a

digestion block with a watch glass placed over the top of

the tube. After reaching room temperature, the contents

of these tubes were transferred to a beaker along with

80.0 mL of deionized water. The samples were finally

titrated with a 0.20 mol L-1 solution of Fe(NH4)2

(SO4)2 � 6H2O in the presence of the ferroin indicator until

the appearance of a violet color.

The determination of TN in the sediment samples, on

the other hand, was performed directly on a CARLO

ERBA 1110 elemental analyzer.

For the determination of TP, dry sediments (approxi-

mately 0.5 g) were initially ignited at 550 �C for 2 h to

convert the OP into orthophosphate, which is the main

form of phosphorus assimilated by aquatic biota (Aspila

et al. 1976; Esteves 1998; Zan et al. 2011). After ignition,

the residues were degraded at room temperature with a

solution of HCl (1.0 mol L-1) in an orbital shaker at

150 rpm for 16 h. The suspensions were then centrifuged

at 3,9299g for a 5-min period. At the end of this proce-

dure, 3.0 mL of the supernatant was removed and diluted

to a volume of 30.0 mL with deionized water (solution A).

The orthophosphate concentration was determined in a

MICRONAL B582 visual spectrophotometer (k =

885 nm), using the ‘‘working reagent’’ (a solution prepared

by combining sulfuric acid, ammonium molybdate, ascor-

bic acid and antimonyl tartrate) (solution B) (Agemian

1997). The absorbance of the samples was recorded 90 min

after the addition of 20.0 mL of solution B to solution A.

The IP content of the sediments was determined by

measuring the orthophosphate released when the dry,

unignited sediments were degraded by a solution of HCl

(1.0 mol L-1). It is important to highlight that this

extraction includes several inorganic subphases, which can

be further known by sequential extraction procedures

(Agemian 1997). The concentrations of TP and IP in the

samples were obtained using an analytical calibration curve

for orthophosphate (r = 0.9995). Finally, the OP content

was calculated from the difference between these mea-

surements (OP = TP - IP).

The determination of phosphorus in this extraction is

based on the reaction of ammonium molybdate with

orthophosphate to form molybdophosphoric acid, which is

then reduced by ascorbic acid to an intensely colored het-

eropoly molybdophosphoric acid complex. The intensity of

produced color is proportional to the orthophosphate con-

centration. The development of the color can be acceler-

ated by the addition of antimony potassium tartrate,

producing a more sensitive system with optimum sensi-

tivity at 885 nm (Agemian 1997).

Determination of the content of organic material,

fine material (silt–clay) and the metal species,

Al, Fe and Mn

Nutrient concentrations can be influenced by the physical

and chemical properties of the sediment and water column

and by the hydrodynamic characteristics of the water body,

which affect the granulometric distribution of sediments

(Svensson and Soderlund 1976; Agemian 1997; Esteves

1998). Thus, the present study also assessed the contents of

OM, fine material (silt–clay) and concentrations of the

metal species, Al, Fe, and Mn, in the sediment samples

studied.

The OM content was determined by ignition of 2.0 g of

sediment at 550 �C for 4 h. Grain size of sediments was

measured on a HORIBA LA-950 particle size distribution

analyzer using the water–quartz refractive index. The metal

species, Al, Fe and Mn, were quantified by flame atomic

absorption spectrometry in a VARIAN SPECTRAA 250

PLUS spectrometer after the sediment samples were diges-

ted in an acidic medium (a mixture of HNO3, H2O2 and HCl)

with heating, according to method 3050 B of the United

States Environmental Protection Agency (US EPA 1996).

Data quality

The quality assurance was controlled by certified reference

materials (CRMs). Blank samples were performed

throughout all the experiments. To evaluate the analytical

precision, all samples were determined in triplicate. The

accuracy of the total analysis was assured using the

E11035-A (EuroVector), BCR-684 (Institute for Reference

Materials and Measurements) and RM 8704 (National

Institute of Standards & Technology) materials. Results

indicated a good agreement between certified and deter-

mined values and the recoveries ranged from 93 to 110 %.

Results and discussion

Total organic carbon

The results of the TOC levels are summarized in Fig. 2. As

can be observed, the nutrient levels varied significantly

between sampling points (21,470–86,584 mg kg-1), where

the highest concentrations were obtained at sampling

points 3 and 7 (86,584 and 71,765 mg kg-1, respectively).

Sampling point 3 displays a greater amount of vegeta-

tion on both banks of the stream. In this sense, the large

trees may provide lignin to the aquatic environment, while

the riparian and aquatic vegetation can provide cellulose.

Certain microorganisms act on both of these substances to

962 Environ Earth Sci (2013) 69:959–968

123

form humic compounds, which can then undergo coagu-

lation and subsequent sedimentation (Steinberg and Melzer

1982; Schafer 1984; Giovanela et al. 2010). Thus, the high

TOC content at this sampling point may be linked to the

presence of OM with high degrees of humification. When

considering local geological features, the slightly acidic

nature of the water promotes the precipitation of humic

acids in the aquatic ecosystem (Esteves 1998).

On the other hand, at sampling point 7, the wetland area

near the sampling region, which consists mainly of grasses

and other decomposing materials, can possibly act as a

source of TOC for the sediment of the Marrecas Stream,

causing this sampling point to also have a high concen-

tration of this nutrient. This may be due to the effects of

rainfall and soil infiltration that carry organic materials to

the water body.

For the other sampling sites, the surrounding vegetation

may represent a less significant source of allochthonous

material, as compared to sampling points 3 and 7. Several

factors may contribute to the lower TOC concentrations in

the other sampling sites. For example, aerobic bacteria that

decompose OM may release a significant amount of less

chemically complex compounds that are rich in carbon and

are possibly dissolved in the water column rather than

being incorporated in the sediment. Additionally, the lim-

ited depth of the Marrecas Stream possibly favors the

elimination of carbon dioxide (produced by respiration of

aquatic organisms) to the atmosphere (Schafer 1984).

Total nitrogen

As can be observed in Fig. 2, the concentrations of TN in

the sediments are practically constant along the examined

river course, ranging from 2,806 to 5,233 mg kg-1. With

respect to this nutrient, the main natural sources include

rain, inorganic allochthonous materials and atmospheric air

(Esteves 1998). Biological fixation of this element, per-

formed by some algae and bacteria, results in the formation

of organic nitrogen (ON). This form of nitrogen may pre-

cipitate and be incorporated into the bottom sediment

(particulate ON) or remain in solution (dissolved ON).

Ammonia and the nitrite and nitrate ions, the main forms of

inorganic nitrogen, are also present in the aquatic envi-

ronment (Steinberg and Melzer 1982).

Because nitrogen is mineralized faster than carbon and

phosphorus, many reduced nitrogenated compounds are

found in the sedimentary column (Anderson and Jensen

1992; Agemian 1997). Therefore, nitrogen can be absorbed

into this environmental compartment, and when it is

summed with the resistant organic nitrogen compounds, it

constitutes the TN measured in the bottom sediment of the

Marrecas Stream.

According to Golterman (2004), nitrogen is encountered

predominantly in the sedimentary column ([90 %) in its

organic form. Thus, one would expect that the TN level for

sediment samples from the Marrecas Stream would be

equivalent to the ON content, as reported in other studies

(Froehner and Martins 2008). However, the sediments

analyzed in this study did not present TN concentrations

equal to the ON concentrations, as shown in Fig. 3.

In this context, nitrogen fixation is possibly more

effective in water than in sediment from the stream. This

would occur because the entire water column of the sam-

pling points analyzed in the Marrecas Stream is illuminated

due to its shallow depth and the low turbidity of water.

Under these conditions, the nitrogen fixing plankton is

more abundant and occupies a greater volume in the system

(Esteves 1998). After the fixation of nitrogen, the process

known as ammonification may follow. In this case, the

Fig. 2 TOC and TN contents (mg kg-1) in the sediment samples:

Black rectangle 1; little gray rectangle 2; rectangle with upper rightto lower left fill 3; rectangle with orthogonal crosshatch fill 4;

rectangle with diagonal crosshatch fill 5; rectangle with vertical fill 6;

dark gray rectangle 7

Fig. 3 Relation between TOC and TN concentrations (mg kg-1) for

sediment samples from the Marrecas Stream microbasin

Environ Earth Sci (2013) 69:959–968 963

123

sediment is the main active site, resulting in the formation

of ammonia. According to Esteves (1998), ammonia is

converted to the ammonium ion in slightly acidic pH and is

then easily assimilated by phytoplankton.

Furthermore, nitrification corresponds to the biological

oxidation of reduced nitrogenated compounds to nitrate

and occurs only in essentially oxygenated environments,

such as in the water column and sediment surface. In the

stream evaluated in this study, the nitrification process may

be hampered by the slow movement of its waters, mainly

caused by the low rainfall during the time of sampling.

According to the Civil Defense of the Rio Grande do Sul

State (Defesa Civil do Estado do Rio Grande do Sul 2011),

the average rainfall in the sampling month was only

52.5 mm. Finally, denitrification, like ammonification,

occurs in the sediment column due to its low oxygen

conditions and the significant amount of organic substrate

(Wetzel 2001).

Total, inorganic and organic phosphorus

The levels of TP, IP and OP in sediments of the Marrecas

Stream are summarized in Fig. 4. It can be seen that

the concentrations of TP (488–1,083 mg kg-1) and IP

(103–505 mg kg-1) varied significantly between sampling

points, whereas the OP levels (381–578 mg kg-1)

remained almost constant. Furthermore, OP concentrations

were greater than those of IP.

Because the levels of OP are greater than those of IP in

the sediments analyzed, Ruttenberg and Goni (1997)

affirmed that this characteristic might be linked to the vast

riparian vegetation adjacent to the sampling points.

According to these authors, this results in better

phosphorus retention by live OM and, therefore, more

effective processing of IP into OP.

In contrast, Mater et al. (2004) have reported that

phosphorus is usually in its inorganic form in the sediment

when the water body does not suffer significant anthropo-

genic interference. According to these authors, the fraction

of IP in relation to TP in these cases is approximately

60 %. However, the sediments analyzed in this study pre-

sented a greater contribution of OP in the TP (Table 1).

Moturi et al. (2005) and Froehner and Martins (2008) have

confirmed that high OP values in river sediments could be

attributed to the discharge of urban sewage. Therefore, one

cannot rule out the possibility that human interference

affects the phosphorus levels in the Marrecas Stream. The

lower ratio IP/TP observed for the sediment collected in the

sampling point 2, for example, suggests a greater amount

of OP in this sample. This behavior can be possibly

attributed to an inflow of domestic sewage that resulted

from recreational activities (camping) and from the resi-

dences situated in the study area.

Taking into consideration the variation in OP concen-

trations, it is possible that there is an inflow of domestic

sewage to the river between sampling points 1 and 2, as

previously mentioned. Below sampling point 2 and through

sampling point 4, the concentration of OP decreases due to

the probable uptake of this nutrient by microorganisms and

the reduced inflow of effluents in this region. Due to the

low depth of the stream and the fact that there is a decrease

in slope between sampling points 2 and 4, it is possible that

the turbulence of the water favors remobilization of OP

from the sediments to the water column, which may assist

in decreasing the concentration in the sedimentary column.

From sampling point 5, the stream begins to receive the

rainwater drainage from the city of Vila Seca (Caxias do

Sul, Rio Grande do Sul State, Brazil), likely including the

domestic sewage of this city and the contribution of waste

from a poultry farm located near the sampled region. These

factors may contribute to the increased concentration of OP

in the stream, especially at sampling point 7.

Physico-chemical interferences on the concentrations

of nutrients in sediments

The content of OM and fine material (silt–clay) and the

concentration of metal species, Al, Fe and Mn, in the

sediment samples are summarized in Table 2. The sedi-

ments that were analyzed presented OM contents ranging

from 10.1 to 29.3 %, which allows their classification as

organic sediments (Esteves 1998; Belo et al. 2010). Based

on the results obtained for the TOC and OM, it is possible

to observe that the TOC concentrations in sampling points

1–5 follow a behavior similar to those obtained for OM.

Moreover, sampling point 3 has the highest levels of TOC

Fig. 4 P species contents (mg kg-1) in the sediment samples: Blackrectangle 1; little gray rectangle 2; rectangle with upper right tolower left fill 3; rectangle with orthogonal crosshatch fill 4; rectanglewith diagonal crosshatch fill 5; rectangle with vertical fill 6; darkgray rectangle 7

964 Environ Earth Sci (2013) 69:959–968

123

and OM. This is because, at this sampling point, a signif-

icant amount of organic material possibly suffers slow

decay as a result of oxygenation of the medium. Sample

point 6 contains a greater OM content and lower TOC

concentration than sample point 7. This may be because

there is a greater dilution of this nutrient at sample point 6

due to increased water turbulence (Froehner and Martins

2008).

The amount of OM in the sediment may also influence the

nitrogen concentration, especially with regard to the deni-

trification step (Esteves 1998). Typically, the highest per-

centage of nitrate associated with the sedimentary column is

eliminated in the form of nitrogen gas (Spooner and Maher

2009). It should be noted that this nitrate can also undergo the

ammonification process and that the resulting ammonium

may be adsorbed by clay minerals from the oxidized portion

of the sediment (Schafer 1984). In the context of the Marr-

ecas Stream, the behavior of the OM content was similar to

TN in sampling points 1–5, while the fine material behavior

was similar to TN in sampling points 4 and 5. A direct

relation between OM and TN and fine material and TN

concentrations was observed. As for the last two points, the

TN concentration may be influenced more substantially by

other factors, such as water oxygenation and temperature

variations, as stated by Schafer (1984).

In addition to the OM and the fine material content

present in the sedimentary column and the aeration and

temperature conditions of the water, there are other inter-

fering factors that can act in nutrient concentrations. In the

case of phosphorus, for example, it is suggested that min-

eralogical characteristics of the area under study (basalts

and rhyolites) contribute to the behavior of this nutrient in

the sampling points of the stream. This is because the rocks

present in the Marrecas Stream microbasin favor the

presence of Fe, Al and Mn in the water column. These

metal species aid in the precipitation process of the

phosphorus with subsequent accumulation in the sediment,

as can be observed by the direct relation of the Al (sam-

pling sites 5 and 6), Fe (sampling sites 1, 2, 4, 5, 6 and 7)

and Mn (sampling sites 4, 5, 6 and 7) concentrations to the

IP content. Finally, as Al, Fe and Mn contents increased at

these sampling points, the IP concentrations also increased

(Agemian 1997; Esteves 1998; Schafer 1984).

Molar ratios between nutrients and their possible

sources

Molar ratios between the concentrations of nutrients have

been used to identify the origin of OM present in a given

ecosystem and to estimate the possible sources of nutrient

input to the environment (Ruttenberg and Goni 1997;

Froehner and Martins 2008). In the case of sediments

whose characteristics may have been influenced by riparian

vegetation present in the water body, TOC/OP levels

between 300 and 1,300 indicate that OM originates from

the tissue of small plants. TOC/OP ratios greater than 1,300

indicate that the OM is derived from wood. Table 3 pre-

sents the results for the TOC/OP molar ratios for sediments

of the Marrecas Stream.

Only sampling points 3 and 7 showed TOC/OP ratios

greater than 300 (520.1 and 320.2, respectively), which

may be linked to the contribution of small terrestrial plants.

For the molar ratios of the other sampling sites, it is sug-

gested that the contribution of domestic sewage to the

stream contributes to an increase in the concentration of OP

and therefore to a decrease in the TOC/OP molar ratio.

This is illustrated by sampling point 5, where the TOC/OP

ratio was the lowest (132.7) compared to the other sam-

pling points. At this location, the stream begins to receive

water from the storm drainage of Vila Seca and domestic

effluents from the same location, which may contribute to

the uptake of OP in the water body.

However, according to Wetzel (2001), the TOC/OP

ratios should be less than 350 for streams, shallow lakes

and reservoirs with low residence time (less than 6

months). Thus, although the stream in question possibly

receives domestic effluents, the region does not seem to

Table 1 Fraction of IP in the content of TP

Sediment samples 1 2 3 4 5 6 7

IP/TP (%) 50.0 17.6 37.2 21.8 35.8 52.4 46.6

Table 2 Results of the organic

matter content, silt–clay

percentage and Al, Fe and Mn

concentrations for the sediment

samples collected in the

Marrecas Stream microbasin

Sediment samples Silt–clay (%) OM (%) Al (g kg-1) Fe (g kg-1) Mn (g kg-1)

1 34.9 11.4 ± 0.15 19.8 ± 0.96 38.3 ± 0.76 0.69 ± 0.01

2 43.2 10.1 ± 0.13 20.6 ± 1.15 34.8 ± 1.28 0.94 ± 0.01

3 39.1 29.3 ± 0.02 19.4 ± 6.63 16.0 ± 0.36 0.17 ± 0.01

4 66.5 15.9 ± 0.02 21.9 ± 1.62 21.5 ± 0.53 0.31 ± 0.01

5 36.8 14.2 ± 0.11 19.4 ± 0.82 24.8 ± 0.77 0.35 ± 0.01

6 30.4 19.2 ± 0.04 19.5 ± 0.96 31.6 ± 0.88 0.66 ± 0.01

7 26.0 17.0 ± 0.11 18.5 ± 1.08 35.5 ± 0.69 0.96 ± 0.02

Environ Earth Sci (2013) 69:959–968 965

123

present high phosphorus contamination that could result in

its eutrophication over the medium or long term.

During the collection of sediments, it should be noted

that a direct observation at each sampling point showed

that the Marrecas Stream displayed no visual aspects of a

eutrophication process, such as growth of macrophytes or

high water turbidity. It should also be noted that the oxy-

genation of water and its temperature, which is relatively

low, could discourage this process. However, the condi-

tions of the aquatic ecosystem in question will probably be

modified after the construction of the reservoir complex. In

this context, in the case that the release of potential

anthropogenic sources of carbon, nitrogen and phosphorus

nutrients continues or intensifies during construction of the

complex, the eutrophication process will probably be

favored in the constructed lentic system.

Comparison of nutrient concentrations

with the literature

Many studies have addressed the quality of sediments by

determining the concentration of nutrients; however, these

studies show different focuses. Thouvenot et al. (2007), for

example, emphasize the modeling of the dynamics of

nutrients at the sediment–water interface in rivers. Wang

et al. (2003a, b) have followed the same approach, but they

emphasize the dynamics of phosphorus instead. Moreover,

the speciation of phosphorus in lake sediments is also

discussed by researchers such as Zhou et al. (2001) and Bai

et al. (2009). Other authors have also studied the behavior

of this nutrient in estuarine sediments (Aviles et al. 2000;

Plagliosa et al. 2005; Marins et al. 2007).

Thus, it can be seen that there are many studies on the

dynamics of nutrients in sediments from various types of

ecosystems. Considering that these studies are quite het-

erogeneous and specific for each environment assessed and

that Brazil does not yet have a law on sediment quality,

comparing the results obtained for the Marrecas Stream

microbasin with the literature is quite difficult. Therefore,

the nutrient concentrations in sediments of the Marrecas

Stream were compared with levels reported for the bottom

sediments of the Joao Correa and Lino streams, and the

Barigui and Itajaı-Acu rivers (Table 4). These environ-

ments were chosen for comparison because they are also

located in southern Brazil, like the area studied in this

work. Additionally, all environments correspond to lotic

environments. Therefore, they may present similar physi-

cochemical and hydrodynamic characteristics.

The Joao Correa Stream is located in the municipality of

Sao Leopoldo (Rio Grande do Sul State, Brazil), a metro-

politan area of Porto Alegre. This stream receives domestic

and industrial effluents, discharges from the pipes of a

waste treatment plant, and part of the urban surface runoff

(Silva 2008). The Lino Stream microbasin, on the other

hand, is located in the municipality of Agudo (Rio Grande

do Sul State, Brazil) and is influenced by the production of

tobacco, which requires intensive soil tillage and the use of

fertilizers and pesticides (Pellegrini et al. 2008).

The Itajaı-Acu River is located in the municipality of

Blumenau (Santa Catarina State, Brazil) and receives

domestic, commercial and industrial wastewater with and

without treatment (Silva et al. 2010). The Barigui River is

located in the metropolitan region of Curitiba (Parana

State, Brazil); the basin area is affected by rural use and the

release of raw sewage in the most urbanized region

(Froehner and Martins 2008).

Comparing the TOC content of sediment from the

Marrecas Stream (21,470–86,584 mg kg-1) with the Lino

Stream (14,000–19,000 mg kg-1) and Barigui River

(5,141–32,359 mg kg-1), it can be seen that the sediments

of the Marrecas Stream are more enriched in this nutrient.

Such behavior may be because the Marrecas Stream is

located in an undeveloped region, with the presence of vast

riparian vegetation along the course of the stream where

the sediment samples were collected. Furthermore, the low

flow rate of the water body results in deposition of fine

material, which contributes to the accumulation of OM

and subsequent humification, a factor that hinders the

Table 3 Molar ratio between TOC and OP concentrations

Sediment

samples

1 2 3 4 5 6 7

TOC/OP

molar ratio

267.3 185.0 520.1 288.0 132.7 278.2 320.2

Table 4 Comparison of the results for TOC, TN and TP in different

bottom sediments and water bodies in Brazil

Sediment source TOC

(mg kg-1)

TN

(mg kg-1)

TP

(mg kg-1)

Marrecas Streama

(Rio Grande do Sul

State)

21,470–86,584 2,806–5,233 488–1,083

Joao Correa Streamb

(Rio Grande do Sul

State)

n.d. n.d. 58–1,077

Lino Streamc (Rio

Grande do Sul State)

14,000–19,000 n.d. 1,070–1,310

Itajaı-Acu Riverd

(Santa Catarina

State)

n.d. 350–2,100 62–378

Barigui Rivere

(Parana State)

5,141–32,359 363–1,779 362–1,586

n.d. not determineda This work, b Silva (2008), c Pellegrini et al. (2008), d Silva et al.

(2010), e Froehner and Martins (2008)

966 Environ Earth Sci (2013) 69:959–968

123

mineralization of organic carbon and facilitates its inter-

action with the sediment (Agemian 1997).

Regarding the results obtained for TN (2,806–5,233 mg

kg-1), the Marrecas Stream is also rich in this nutrient

compared to the Itajaı-Acu (350–2,100 mg kg-1) and

Barigui rivers (363–1,779 mg kg-1). In the Marrecas

Stream, it is probable that the ammonification and deni-

trification processes are more effective due to the low rates

of oxygenation in the sedimentary column. However, in

both rivers, it is suggested that nitrification is the nitrogen

cycling stage that is most facilitated by the hydrodynamic

conditions of these ecosystems, possibly due to greater

aeration. Thus, large amounts of nitrate may remain dis-

solved, not adding to the TN levels in the sedimentary

column (Esteves 1998).

Regarding the TP content, the lowest concentration

obtained for sediments of the Marrecas Stream

(488 mg kg-1) was greater than the lower concentrations

obtained for the Joao Correa Stream (58 mg kg-1) and the

Itajaı-Acu and Barigui rivers (62 and 362 mg kg-1,

respectively). The highest concentration obtained for the

sediments of the Marrecas Stream (1,083 mg kg-1) was

higher than the highest concentration of TP in the Joao

Correa Stream (1,077 mg kg-1) and Itajaı-Acu River

(378 mg kg-1). In contrast, the Barigui River showed a

maximum TP limit (1,586 mg kg-1) higher than that

obtained for the Marrecas Stream. Only the Lino Stream

showed both minimum and maximum concentrations

(1,070 and 1,310 mg kg-1, respectively) that were greater

than the limits obtained for the Marrecas Stream.

The high TP levels in the Marrecas Stream sediment

samples, compared to those of the Joao Correa Stream and

the Itajaı-Acu and Barigui rivers, may be due to the fact

that the Marrecas Stream is located in a region with

chemical, physicochemical and hydrodynamic character-

istics favoring the precipitation of phosphorus (with sub-

sequent accumulation in the sediment), such as the

presence of fine material (silt–clay) and OM, as well as Fe,

Al and Mn species (Esteves 1998). Finally, the high TP

concentrations reported for sediments of the Lino Stream

may be associated with agricultural influence on the

microbasin region, as shown previously.

Conclusions

The purpose of this preliminary study was to assess the

levels of TOC, NT, TP, IP and OP in sediments that were

collected from a southern Brazilian microbasin. The results

indicated that the physico-chemical properties of the

samples act directly on the concentration of the nutrients.

The OM can influence the TOC and TN nutrients while the

grain size, in turn, may interfere with the TN contents. The

metal species, on the other hand, can favor the increase of

IP concentrations in the sedimentary column.

Furthermore, a direct relation was observed of the TOC

and IP concentrations to the vast riparian vegetation pres-

ent in areas adjacent to the sampling points and to the

physico-chemical properties of the water and sedimentary

columns, respectively. Moreover, the results obtained for

TN suggest that its concentration possibly suffers inter-

ference from the temperature of the water and its oxy-

genation, in addition to other biological activities. On the

other hand, one cannot rule out human interference, mainly

in the levels of OP, possibly due to the inflow of domestic

sewage to the stream. Compared to some studies in liter-

ature, the Marrecas Stream microbasin showed high levels

of TOC, TN and TP, suggesting significant interference

from the vast riparian vegetation and possible inflow of

domestic sewage and waste from a poultry farm located

near the sampled region.

Acknowledgments The authors acknowledge the Conselho Nac-

ional de Desenvolvimento Cientıfico e Tecnologico (National Council

for Scientific and Technological Development—CNPq) for its

financial support and the Fundacao de Amparo a Pesquisa do Estado

do Rio Grande do Sul (Foundation for Research Support of the State

of Rio Grande do Sul—FAPERGS) for the scientific initiation

scholarship.

References

Agemian H (1997) Determination of nutrients in aquatic sediments.

In: Mudroch A, Azcue JM, Mudroch P (eds) Manual of physico-

chemical analysis of aquatic sediments. CRC, New York,

pp 175–213

Anderson FO, Jensen HS (1992) Regeneration of inorganic phospho-

rus and nitrogen from seston in a freshwater sediment. Hydro-

biologia 228:71–81

Antunes M, Dillon DB, Crespo JS, Giovanela M (2008) Avaliacao

dos parametros fısico-quımicos e do teor de metais em amostras

de uma microbacia gaucha. Geochim Brasiliensis 22:178–188

Aspila KI, Agemian H, Chau ASY (1976) A semiautomated method

for the determination of inorganic, organic and total phosphate in

sediments. Analyst 101:187

Aviles A, Becerra J, Palomo L, Izquierdo JJ, Clavero V, Niell EX

(2000) Distribution of different phosphorus fractions in the

sediment of Palmones River (Southern Spain) during a dry

season. Limnetica 19:31–38

Bai X, Ding S, Fan C, Liu T, Shi D, Zhang L (2009) Organic phosphorus

species in surface sediments of a large, shallow, eutrophic lake,

Lake Taihu, China. Environ Pollut 157:2507–2513

Baumgarten MGZ, Niencheski LFH, Veeck L (2001) Nutrientes na

coluna da agua e na agua intersticial de sedimentos de uma

enseada rasa estuarina com aportes de origem antropica (RS–

Brasil). Atlantica 23:101–116

Belo A, Quinaia SP, Pletsch AL (2010) Avaliacao da contaminacao

de metais em sedimentos superficiais das praias do Lago de

Itaipu. Quım Nova 33:613–617

Defesa Civil do Estado do Rio Grande do Sul (2011) Consulta de ındices

pluviometricos. Available at http://www2.defesacivil.rs.gov.br/

estatıstica/pluviometro_consulta.asp

Environ Earth Sci (2013) 69:959–968 967

123

Esteves FA (1998) Fundamentos de Limnologia. Interciencia, Rio de

Janeiro

Froehner S, Martins RF (2008) Avaliacao da composicao quımica de

sedimentos do rio Barigui na regiao metropolitana de Curitiba.

Quım Nova 31:2020–2026

Giovanela M, Crespo JS, Antunes M, Adamatti DS, Fernandes AN,

Barison A, Silva CWP, Guegan R, Motelica-Heino M, Sierra

MMD (2010) Chemical and spectroscopic characterization of

humic acids extracted from the bottom sediments of a Brazilian

subtropical microbasin. J Mol Struct 981:111–119

Golterman HL (2004) The chemistry of phosphate and nitrogen

compounds in sediments. Kluwer Academic Publishers, Dordrecht

Grenz C, Denis L, Pringault O, Fichez R (2010) Spatial and seasonal

variability of sediment oxygen consumption and nutrient fluxes

at the sediment water interface in a sub-tropical lagoon (New

Caledonia). Mar Pollut Bull 61:399–412

House WA, Denison FH (2002) Total phosphorus content of river

sediments in relationship to calcium, iron and organic matter

concentrations. Sci Total Environ 282–283:341–351

Marins RV, Paula Filho FJ, Rocha CAS (2007) Geoquımica de

fosforo como indicadora da qualidade ambiental e dos processos

estuarinos no Rio Jaguaribe—Costa Nordeste Oriental Brasileira.

Quım Nova 30:1208–1214

Mater L, Alexandre MR, Hansel FA, Madureira LAS (2004)

Assessment of lipid compounds of phosphorus in mangrove

sediments of Santa Catarina Island, SC, Brazil. J Braz Chem Soc

15:725–734

Moturi MCZ, Rawat M, Subramanian V (2005) Distribution and

partitioning of phosphorus in solid waste and sediments from

drainage canals in the industrial belt of Delhi, India. Chemo-

sphere 60:237–244

Mozeto AA, Soares A (2006) Projeto Qualised—Determinacao de

Fluxos de Nutrientes e Outras Especies Quımicas na Interface

Sedimento-Agua de Ambientes Aquaticos Lenticos e Lımnicos.

Cubo, Sao Carlos

Nyenje PM, Foppen JW, Uhlenbrook S, Kulabako R, Muwanga A

(2010) Eutrophication and nutrient release in urban areas of sub-

Saharan Africa—a review. Sci Total Environ 408:447–455

Ouyang Y (2003) Simulating dynamic load of naturally occurring

TOC from watershed into a river. Water Res 37:823–832

Pellegrini JBR, Rheinheimer DS, Goncalves CS, Copetti ACC,

Bortoluzzi EC (2008) Adsorcao de fosforo em sedimentos e sua

relacao com a acao antropica. R Bras Ci Solo 32:2639–2646

Plagliosa PR, Fonseca AF, Bosquilha GE, Braga ES, Barbosa FAR

(2005) Phosphorus dynamics in water and sediments in urban-

ized and non-urbanized rivers in Southern Brazil. Mar Pollut Bul

50:965–974

Rheinheimer DS, Campos BC, Giacomini SJ, Conceicao PC,

Bortoluzzi EC (2008) Comparacao de metodos de determinacao

de carbono organico total no solo. R Bras Ci Solo 32:435–440

Roessink I, Koelmans AA, Brock TCM (2008) Interactions between

nutrients and organic micro-pollutants in shallow freshwater

model ecosystems. Sci Total Environ 406:436–442

Ruttenberg KC, Goni MA (1997) Phosphorus distribution, C:N:P

ratios, and d13Coc in Artic, temperate, and tropical coastal

sediments: tools for characterizing bulk sedimentary organic

matter. Mar Geol 139:123–145

Schafer A (1984) Fundamentos de ecologia e biogeografia das aguas

continentais. UFRGS, Porto Alegre

Schneider VE, Schmitz D, Cemin G, Silva MD, Panizzon T, Bortolin

TA, Finotti AR (2009) Usos da agua na Bacia do Arroio

Marrecas—RS, in: Anais Eletronicos do XVIII Simposio

Brasileiro de Recursos Hıdricos. ABRH, Campo Grande

Silva IM (2008) Comparacao dos ındices de qualidade da agua e usos

do fator de contaminacao e ındice de geoacumulacao para os

sedimentos da Microbacia do Arroio Joao Correa. Dissertation,

Universidade do Vale do Rio dos Sinos

Silva MR, Goncalves AC Jr, Pinheiro A, Benvenutti J, Susin J (2010)

Distribuicao de nutrientes em sedimentos fluviais do rio Itajaı-

Acu, Blumenau, SC, Brasil. Ambi-Agua 5:102–113

Souza SNP, Fadini PS, Pereira-Filho ER (2009) Determinacao de Cd

e Pb: avaliacao de sedimentos do Rio Jundiaı—SP e Ribeirao

Piraı—SP e lodo proveniente de uma estacao de tratamento de

esgotos. Quım Nova 32:2367–2372

Spooner DR, Maher W (2009) Benthic sediment composition and

nutrient cycling in an intermittently closed and open Lake

Lagoon. J Marine Syst 75:33–45

Steinberg C, Melzer A (1982) Stoffkreislaufe in binnengewassern.

Bayerisches Landesamt fur Wasserwirtschaft, Munchen

Svensson BH, Soderlund R (1976) Nitrogen, phosphorus and

sulphur—global cycles, SCOPE 7. Wiley, New York

Thouvenot M, Billen G, Garnier J (2007) Modelling nutrient

exchange at the sediment–water interface of river systems.

J Hydrol 341:55–78

U.S. EPA (1996) Method 3050B: acid digestion of sediments, sludges

and soils. Available at http://www.epa.gov/wastes/hazard/

testmethods/sw846/pdfs/3050b.pdf

Wang H, Appan A, Gulliver JS (2003a) Modeling of phosphorus

dynamics in aquatic sediments: I—model development. Water

Res 37:3928–3938

Wang H, Appan A, Gulliver JS (2003b) Modeling of phosphorus

dynamics in aquatic sediments: II—examination of model

performance. Water Res 37:3939–3953

Wetzel RG (2001) Limnology: lake and river ecosystems. Academic

Press, San Diego

Zan F, Huo S, Xi B, Li Q, Liao H, Zhang J (2011) Phosphorus

distribution in the sediments of a shallow eutrophic lake, Lake

Chaohu, China. Environ Earth Sci 62:1643–1653

Zhang TX, Wang XR, Jin XC (2007) Variations of alkaline

phosphatase activity and P fractions in sediments of a shallow

Chinese eutrophic lake (Lake Taihu). Environ Pollut

150:288–294

Zhang R, Wu F, Liu C, Fu P, Li W, Wang L, Liao H, Guo J (2008)

Characteristics of organic phosphorus fractions in different

trophic sediments of lakes from the middle and lower reaches of

Yangtze River region and Southwestern Plateau, China. Environ

Pollut 152:366–372

Zhou Q, Gibson CE, Zhu Y (2001) Evaluation of phosphorus

bioavailability in sediments of three contrasting lakes in China

and the UK. Chemosphere 42:221–225

968 Environ Earth Sci (2013) 69:959–968

123